The present invention relates to an opening and closing valve which opens and closes a valve seat in a valve box by a valve element provided at a lower end of a valve stem by moving the valve stem upward and downward.
In an opening and closing valve for controlling the flow of high-pressure fluids and corrosive fluids, a packing is interposed between a journaling portion of a valve box and a valve stem in order to prevent the fluids from leaking to the outside. Japanese Utility Model Publication No. H3-77880 discloses, for example, an opening and closing valve in which a packing gland which presses the packing is provided via a packing gland ring above the packing interposed between the journaling portion of the valve box and the valve stem; a yoke sleeve inserted into a yoke portion of the valve box and screwed into the valve stem is provided above the packing gland and; and the opening and closing valve opening and closing a valve seat in a valve box by a valve element provided at a lower end of the valve stem by moving the valve stem upward and downward by rotating a handle fitted into the yoke sleeve.